Pilot operated valves have long been used in a variety of applications. One application is that of pressure regulation wherein it is desirable to control the position of a valve dependent upon the relative pressures on the inlet and outlet sides of the valve. Most frequently, this is accomplished by means of inlet and outlet pilot signals.
In a common application, the pilot operated valve controls the pressure applied to a valve actuator by adjusting a variable orifice with a poppet. The position of the poppet relative to the orifice is determined, at least in part, by the relative pressure on the inlet and outlet sides of the valve, i.e., by the inlet and outlet pilot signals. In addition, the poppet will typically be biased toward a closed position relative to the variable orifice.
In making a pilot operated valve of this type, a problem is to provide convenient adjustability for meeting different operating conditions. It is also difficult to minimize leakage and optimize response time since alignment problems are usually presented and the constructions of such valves are such that valve opening and closing times during transients are inherently long. Moreover, pilot operated valves are usually difficult to manufacture, assemble and adjust.
While overcoming problems of this type, it is also desirable to provide a construction wherein friction losses and hysteresis losses are minimized. It is also desirable that the valve system have rapid dynamic response and adjustability in more than one area. Further, it is desirable that the valve system be of modular construction and compact size for ready connection to an actuator housing.
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects.